Arthur W. Upfield 
The Mystery of Swordfish Reef [EPUB ebook] 

An intriguing case for Inspector Napoleon Bonaparte begins on a calm October day in an Australian seaside near Bermagui. Three men set out to sea for a day’s fishing… and do not return. Despite intensive searches, no trace of the men or their boat is found, until, weeks later, a passing trawler hauls in a gruesome catch — the head of one of the missing fishermen. It is quite clear that its owner was murdered with a pistol shot. But by whom, and why, is for Bony to find out.
A thriller with a new kind of thrill. — Sheffield Morning Telegraph